The fuel gas for gas turbine power generation is required to have such technical indicators as higher heat value and higher purity; otherwise the gas turbine is unable to perform continuous normal operation. To reach the technical indicators, fuel materials for preparation of fuel gas are fine lump coal, coke or high-grade coal dust, coal water slurry or fuel oil suitable for spraying. However, resources of these raw materials are limited and the cost for preparation of fuel gas is high. Since it is difficult to maintain the normal operation of gas turbine, the coal-based gas turbine power generation has not been improved. In order to reduce the cost of gas turbine power generation, methods related to pressurized water coal gas, dry-fired coal gas and sprayed pure special-purpose gas generating coal dust for the gas turbine are being adopted. However, these methods still have problem, for example, to reduce the power-production cost of gas turbine.